Outdoor unit

ABSTRACT

An outdoor unit includes a part of a main refrigerant circuit formed by connecting a compressor, an indoor-unit-side heat exchanger, an electronic expansion valve, and an outdoor-unit-side heat exchanger via a main refrigerant pipe, a bypass circuit bypassing refrigerant discharged from the compressor and flowing through the main refrigerant circuit, a controller configured to control a flow rate of refrigerant flowing through the main refrigerant circuit and a flow rate of refrigerant flowing through the bypass circuit, an outdoor unit base supporting the compressor and the outdoor-unit-side heat exchanger, a snow-protection frame provided below the outdoor unit base, the snow-protection frame supporting the outdoor unit base, and a load heating unit provided to the snow-protection frame the load heating unit and configured to heat a portion around the load heating unit by exchanging heat between a heat medium flowing through the load heating unit and the refrigerant flowing through the bypass circuit.

TECHNICΔL FIELD

The present invention relates to an outdoor unit.

BACKGROUND ART

When, for example, an air-conditioning apparatus is configured to be a heat-pump system, a refrigerant circuit is configured, and a refrigeration cycle is formed.

In the refrigerant circuit, for example, an outdoor unit including a compressor and an outdoor-unit-side heat exchanger, and an indoor unit including an expansion valve and an indoor-unit-side heat exchanger, are connected by a refrigerant pipe. That is, the refrigerant circuit has a configuration in which the outdoor unit, which is a heat-source-side unit, and the indoor unit, which is a load-side unit, are connected by the refrigerant pipe, so that refrigerant circulates through the refrigerant circuit.

The refrigerant circuit, for example, receives heat from air in an air-conditioned space, which is a target of heat exchange, at the indoor-unit-side heat exchanger, and therefore causes refrigerant to evaporate. Furthermore, the refrigerant circuit, for example, transfer heat to air in an air-conditioned space, which is a target of heat exchange, at the indoor-unit-side heat exchanger, and therefore causes refrigerant to condense. That is, the air-conditioning apparatus changes the pressure, temperature, and other conditions of the refrigerant flowing through the refrigerant circuit, and therefore conditions the air in the air-conditioned space.

Here, the outdoor unit is surrounded by a housing. The outdoor-unit-side heat exchanger is accommodated in the housing, and an outdoor unit base is provided below the outdoor-unit-side heat exchanger. The outdoor-unit-side heat exchanger is placed on the outdoor unit base. The outdoor unit base has a drain hole.

When drain water or other liquid generated by a defrosting or other operations is discharged out of the housing through the drain hole, that is, for example, when the air-conditioning apparatus performs heating operation, the outdoor-unit-side heat exchanger functions as an evaporator. Thus, if heating operation is performed when the outside air temperature is low, drain water or other liquid retained in the outdoor unit base turns into ice and covers the drain hole. If the drain hole is covered, drain water or other liquid is not discharged out of the outdoor unit base and therefore continues to retain in the outdoor unit base. Therefore, freezing further proceeds. As a result, ice formation or other phenomena occurs. Since ice formation interrupts the flow of air passing through the outdoor-unit-side heat exchanger, efficient heat exchange cannot be achieved.

An air-conditioning apparatus in which an electric heater is installed around a drain hole has been available as one of air-conditioning apparatuses of related art. The electric heater is heated when being supplied with electric power, and melts ice present in the outdoor unit base. That is, an air-conditioning apparatus among air-conditioning apparatuses of related art that prevents water retaining in an outdoor unit base from turning into ice has been available (see, for example, Patent Literature 1).

However, although an electric heater provided on the air-conditioning apparatus of related art is able to prevent water retaining in the outdoor unit base from turning into ice, the drain hole of the outdoor unit base is closed by the influence of snow even if the electric heater is used in regions where the amount of snow accumulation is large and snow reaches the bottom of the outdoor unit base. Therefore, an outdoor unit of related art exhibits a poor drainage performance.

It is necessary to provide a snow-protection frame below the outdoor unit so that a height tall enough for snow not to reach the outdoor unit base can be ensured.

In cold regions where the amount of snow accumulation is large, in general, load heating is utilized to melt snow (see, for example, Patent Literature 2).

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent No. 3882910 (paragraph [0012])

Patent Literature 2: Japanese Patent No. 4517556 (paragraph [0022])

SUMMARY OF INVENTION Technical Problem

As described above, as measures regarding accumulation of snow in cold regions, for example, a snow-protection frame has been provided so that snow may not reach the outdoor unit base, an electric heater has been operated so that drain water or other liquid retaining in the outdoor unit base may not turn into ice, or load heating has been arranged so that snow accumulated on the ground may be melted.

However, even if the electric heater can prevent drain water or other liquid retaining in the outdoor unit base from turning into ice, when snow reaches the outdoor unit base, the electric heater has not been able to prevent the drain hole from being covered due to the influence of snow. Therefore, it has been necessary to ensure a height tall enough for snow not to reach the bottom of the outdoor unit base by using the snow-protection frame.

Since, for example, the amount of snow accumulation is assumed to be 5 (m) or more in a region where the amount of snow accumulation is large, to ensure that the snow-protection frame has a sufficient height, it is required for the snow-protection frame to have a height taller than 5 (m). Therefore, when a sufficient height of the snow-protection frame is ensured, the outdoor unit is placed at a high position, and the service performance therefore degrades. Thus, when the influence of snow on the outdoor unit base is avoided by the use of the snow-protection frame, the service performance cannot be improved.

Furthermore, if the snow-protection frame is provided and the electric heater is provided below the outdoor unit, since there are increased requirements for consideration of the safety in operation of the electric heater, the operation cost increases.

Furthermore, when load heating is provided on the entire ground around the outdoor unit to melt snow accumulated on the ground, the arrangement cost increases.

That is, there is a problem that water cannot be prevented from turning into ice in the outdoor unit base while the service performance is improved and a low cost is achieved.

The present invention has been made to solve the problems described above, and an object of the present invention is to provide an outdoor unit that is able to prevent water from turning into ice in the outdoor unit base while the service performance is improved and a low cost is achieved.

Solution to Problem

An outdoor unit according to the present invention includes a part of a first refrigerant circuit formed by connecting a compressor, an indoor-unit-side heat exchanger, an expansion device, and an outdoor-unit-side heat exchanger via a refrigerant pipe, a second refrigerant circuit bypassing refrigerant discharged from the compressor and flowing through the first refrigerant circuit, a controller configured to control a flow rate of refrigerant flowing through the first refrigerant circuit and a flow rate of refrigerant flowing through the second refrigerant circuit, an outdoor unit base supporting the compressor and the outdoor-unit-side heat exchanger, a snow-protection frame provided below the outdoor unit base, the snow-protection frame supporting the outdoor unit base, and a load heating unit provided to the snow-protection frame, the load heating unit configured to heat a portion around the load heating unit by exchanging heat between a heat medium flowing through the load heating unit and the refrigerant flowing though the second refrigerant circuit.

Advantageous Effects of Invention

According to the present invention, by providing a load heating unit that utilizes a refrigeration cycle on a snow-protection frame, snow accumulated on the snow-protection frame may be melted, while the service performance is improved and a low cost is achieved. Therefore, the present invention has an effect of preventing water from turning into ice in the outdoor unit base, while the service performance is improved and a low cost is achieved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example of a schematic configuration of an air-conditioning system 1 according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating an example of an outer shape of an outdoor unit 7 according to Embodiment 1 of the present invention.

FIG. 3 is a diagram illustrating an example of a functional configuration of a controller 51 according to Embodiment 1 of the present invention,

FIG. 4 is a flowchart for explaining a control example of the controller 51 according to Embodiment 1 of the present invention.

FIG. 5 is a diagram illustrating an example of the schematic configuration of the air-conditioning system 1 according to Embodiment 2 of the present invention.

FIG. 6 is a diagram illustrating an example of a functional configuration of the controller 51 according to Embodiment 2 of the present invention.

FIG. 7 is a flowchart for explaining a control example of the controller 51 according to Embodiment 2 of the present invention.

FIG. 8 is a diagram illustrating an example of a functional configuration of the controller 51 according to Embodiment 3 of the present invention.

FIG. 9 is a flowchart for explaining a control example of the controller 51 according to Embodiment 3 of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Steps describing a program for executing an operation of an embodiment of the present invention include not only processing executed in time series in the described order but also processing executed in parallel or discretely, not always in time series.

Furthermore, each function described in the embodiments may be implemented by hardware or software. That is, each block diagram described in the embodiments may be considered as a block diagram of hardware or may be considered as a functional block diagram of software. For example, each block diagram may be implemented by hardware such as a circuit device or may be implemented by software executed on an arithmetic device such as a processor, which is not illustrated in figures.

Furthermore, each block of block diagrams described in the embodiments only need to execute the function thereof, and configurations of the blocks do not need to be separated from each other. In each of Embodiments 1 to 3, items not particularly described are common among Embodiments 1 to 3, and the same functions and configurations are described using the same reference signs. Furthermore, Embodiments 1 to 3 may be executed individually or in combination thereof. In any case, advantageous effects described below are achieved. Furthermore, various specific setting examples described in the embodiments are merely examples, and the present invention is not particularly limited to these examples.

Embodiment 1 Configuration of Embodiment 1

FIG. 1 is a diagram illustrating an example of a schematic configuration of an air-conditioning system 1 according to Embodiment 1 of the present invention. As illustrated in FIG. 1, the air-conditioning system 1 includes an air-conditioning apparatus 2 and a load heating unit 3. The load heating unit 3, whose details will be described later, may be commercially available and is configured to be attachable to the air-conditioning apparatus 2 as an optional component.

The air-conditioning apparatus 2 includes a main refrigerant circuit 4, a bypass circuit 5, and a load heating heat exchanger 6. The main refrigerant circuit 4 includes, for example, a compressor 11, a four-way valve 12, a gas operation valve 13, an indoor-unit-side heat exchanger 14, an electronic expansion valve 15, a liquid operation valve 16, a flow control device 17, a heat exchanger 18, an outdoor-unit-side heat exchanger 19, an accumulator 20, and other components. The bypass circuit 5 includes, for example, a bypass pipe 31, a bypass circuit solenoid valve 32, a bypass circuit electronic expansion valve 34, a bypass circuit temperature sensors, and other components.

Next, a specific configuration of the air-conditioning apparatus 2 will be described. The air-conditioning apparatus 2 includes an outdoor unit 7 and an indoor unit 9. Among these components, the outdoor unit 7 includes a part of the main refrigerant circuit 4 and functions as a heat-source-side unit. The outdoor unit 7 includes, for example, the compressor 11, the four-way valve 12, the gas operation valve 13, the liquid operation valve 16, the flow control device 17, the heat exchanger 18, the outdoor-unit-side heat exchanger 19, the accumulator 20, and other components. Among the above components, the outdoor-unit-side heat exchanger 19 functions as a heat-source-side heat exchanger.

The outdoor unit 7 includes a controller 51 as a control function. The controller 51 is, for example, a functional configuration that is implemented on a control board accommodated in an electric component box of the outdoor unit 7, which is not illustrated in the figure. The details of the functional configuration of the controller 51 will be described later with reference to FIG. 3, but in short, the controller 51 is implemented on the outdoor unit 7 as a functional configuration for controlling a driving component of the outdoor unit 7 depending on various sensing results. Furthermore, the controller 51 includes, as a physical configuration, a switching unit 52 that includes various switches such as a dip switch and a rotary switch, which are not illustrated in the figure. Such various switches are accommodated as the switching units 52 in the electric component box, which is not illustrated in the figure, and are used for changing various settings.

The outdoor unit 7 includes the bypass circuit 5, which is explained above. A detection result of the bypass circuit temperature sensor 35 of the bypass circuit 5 is transmitted to the controller 51. For example, the bypass circuit temperature sensor 35 is provided on the outlet side of the load heating heat exchanger 6, and detects the outlet temperature of the load heating heat exchanger 6. The bypass circuit temperature sensor 35 converts such a detection result into a detection signal based on a preset communication protocol, and transmits the detection signal to the controller 51. In contrast, the indoor unit 9 includes another part of the main refrigerant circuit 4 and functions as a load-side unit. The indoor unit 9 includes, for example, the indoor-unit-side heat exchanger 14, the electronic expansion valve 15, and other components. Among the above components, the indoor-unit-side heat exchanger 14 functions as a use-side heat exchanger.

Based on the assumption of the above configuration, a further specific configuration of the air-conditioning apparatus 2 will be described. First, specific various configurations of the outdoor unit 7 will be described. The compressor 11 compresses sucked refrigerant, and discharges the compressed refrigerant. For example, an inverter device, which is not illustrated in the figure, is provided in the controller 51, which will be described later, and an operation frequency is transmitted from the controller 51 to the compressor 11. The controller 51 changes the operation frequency in a desired manner to control the capacity of the compressor 11, that is, the delivery amount of refrigerant per unit time by the compressor 11, within the range of specifications of the compressor 11 in a desired manner.

The four-way valve 12 switches the flow of refrigerant between a cooling operation time and a heating operation time, based on a signal transmitted from the controller 51. The gas operation valve 13 controls the outflow amount of refrigerant flowing out of the outdoor unit 7 and the inflow amount of refrigerant flowing into the outdoor unit 7. Specifically, the gas operation valve 13 controls the outflow amount and the inflow amount of gas refrigerant, such as gas single-phase refrigerant or two-phase gas-liquid refrigerant whose main component is gas refrigerant. The liquid operation valve 16 controls the inflow amount of refrigerant flowing into the outdoor unit 7 and the outflow amount of refrigerant flowing out of the outdoor unit 7. Specifically, the liquid operation valve 16 controls the inflow amount and the outflow amount of liquid refrigerant, such as liquid single-phase refrigerant or two-phase gas-liquid refrigerant whose main component is liquid refrigerant.

The flow control device 17 is provided at a sub-refrigerant pipe 23 that branches off from a main refrigerant pipe 22. The sub-refrigerant pipe 23 is, for example, elastic with a longitudinal shape. One end of the sub-refrigerant pipe 23 has one connection port, and the other end of the sub-refrigerant pipe 23 has separated two connection ports. One end of the sub-refrigerant pipe 23 is connected to the main refrigerant pipe 22 on the side of the liquid operation valve 16. A first one of the other end is connected between the four-way valve 12 and the accumulator 20, and a second one of the other end is connected on a downstream side of the bypass circuit electronic expansion valve 34. The opening degree of the flow control device 17 may be changed, and the flow control device 17 includes a valve for adjusting the flow rate. The heat exchanger 18 exchanges heat between refrigerant flowing through the main refrigerant pipe 22 and refrigerant flowing through the sub-refrigerant pipe 23. The state of the refrigerant flowing through the sub-refrigerant pipe 23 is adjusted by the flow control device 17.

The outdoor-unit-side heat exchanger 19 exchanges heat between refrigerant and air. Specifically, the outdoor-unit-side heat exchanger 19 exchanges heat between the refrigerant flowing through the main refrigerant pipe 22 and outdoor air sucked from the outdoor unit 7 using a fan for the outdoor unit 7, which is not illustrated in the figure. The outdoor-unit-side heat exchanger 19 functions as an evaporator, for example, during heating operation, and thus evaporates and gasifies refrigerant. The outdoor-unit-side heat exchanger 19 functions as a condenser, for example, during cooling operation, and thus condenses and liquefies refrigerant.

The load heating heat exchanger 6 connects the bypass pipe 31 that forms the bypass circuit 5 and a load heating refrigerant pipe 44 that forms the load heating unit 3. When the bypass pipe 31 and the load heating refrigerant pipe 44 are connected, the load heating heat exchanger 6 exchanges heat between refrigerant flowing through the bypass pipe 31 and liquid, which is a heat medium flowing through the load heating refrigerant pipe 44. By using, for example, antifreeze as liquid that flows through the load heating refrigerant pipe 44, the liquid that flows through the load heating refrigerant pipe 44 can be prevented from being frozen even in cold regions.

Although an example in which liquid antifreeze is used as an example of a heat medium that flows through the load heating refrigerant pipe 44 has been explained above, the present invention is not particularly limited to this example. Gas may be used as long as it is a heat medium and is not frozen in cold regions.

The load heating heat exchanger 6 includes, for example, two connection ports that connect the bypass pipe 31 and two connection ports that connect the load heating refrigerant pipe 44. Each of the connection ports provided at the load heating heat exchanger 6 is provided with a member that allows connection with various pipes. For example, when the load heating unit 3 is optionally attached to the load heating heat exchanger 6, the member that allows connection with various pipes fixes the load heating refrigerant pipe 44. When the load heating unit 3 is not optionally attached to the load heating heat exchanger 6, the individual connection ports provided at the load heating heat exchanger 6 may be covered with caps having shapes corresponding to the connection ports.

The member that allows connection with various pipes may be, for example, a longitudinal connection pipe that has two connection ports, and each of the two connection ports may be, for example, made of covering members that cover around the connection pipe, able to connect different types of metal, and made of materials with a high resistance to corrosion.

As described above, the load heating heat exchanger 6 exchanges heat between refrigerant flowing through the bypass pipe 31 and antifreeze flowing through the load heating refrigerant pipe 44. Specifically, when the load heating unit 3 becomes necessary during heating operation, by opening the bypass circuit solenoid valve 32 of the bypass pipe 31, the controller 51 causes the load heating heat exchanger 6 to exchange heat between the refrigerant and the antifreeze.

As a result, the refrigerant flowing through the bypass pipe 31 condenses and liquefies, and thus turns into liquid refrigerant. The accumulator 20 is formed with a configuration to store excess refrigerant, and is connected to the bypass pipe 31. Therefore, the liquid refrigerant condensed at the load heating heat exchanger 6 flows into the accumulator 20, and is accumulated in the accumulator 20.

The load heating unit 3 includes, for example, a heating member 41 and a pump 42. The heating member 41 includes, for example, a heating pipe 43. Materials, outer shapes, cross-sectional shape, and other features of the heating member 41 are not particularly limited. The heating member 41 may have a high cold resistance and a high durability. The arrangement configuration of the heating pipe 43 is not particularly limited. In order that heat of the heating pipe 43 may be easily transmitted around the load heating unit 3, the heating pipe 43 may be arranged, for example, in a meander shape. The pump 42 allows, for example, antifreeze that flows through the heating pipe 43 to circulate. Driving of the pump 42 is controlled by the controller 51, which will be described later.

Furthermore, as described above, the load heating heat exchanger 6 exchanges heat between refrigerant and antifreeze, and therefore the antifreeze flowing through the load heating refrigerant pipe 44 is heated. Furthermore, since the pump 42 is driven, the antifreeze flowing through the load heating refrigerant pipe 44 circulates in the load heating unit 3. Therefore, the heated antifreeze passes through the heating pipe 43 due to driving of the pump 42, and circulates in the load heating unit 3. Thus, the heating member 41 may heat a portion around the heating member 41. That is, the liquid that circulates in the load heating unit 3 is a heat medium, and antifreeze that is not frozen even in cold regions is used as the heat medium. Therefore, by exchanging heat between refrigerant and a heat medium at the load heating heat exchanger 6, the load heating unit 3 may heat the portion around the load heating unit 3.

Next, the bypass circuit 5 will be specifically explained. The bypass circuit electronic expansion valve 34 is configured to change the opening degree thereof so that the flow rate of refrigerant flowing through the bypass pipe 31 may be adjusted. The controller 51 obtains the degree of subcooling based on a detection result of the bypass circuit temperature sensor 35 and the saturation temperature of high pressure, and adjusts the opening degree of the bypass circuit electronic expansion valve 34 on the basis of the obtained degree of subcooling.

The bypass circuit solenoid valve 32 is a relay for opening and closing a valve, and adjusts whether or not refrigerant flowing through the bypass pipe 31 is to be caused to pass through the bypass circuit solenoid valve 32. The controller 51 calculates the distance ΔL between an outdoor unit base 62, which will be described later, and snow 55, based on a detection result of a snowfall sensor 91, which will be described later. The controller 51, whose details of control will be described later, determines, depending on the calculated distance ΔL, whether or not to shift a mode to a first snow-removing mode for causing refrigerant to circulate in the bypass circuit 5. When the first snow-removing mode is entered, the controller 51 opens the bypass circuit solenoid valve 32 to cause refrigerant to flow through the bypass circuit 5, and drives the pump 42 to cause antifreeze to circulate in the load heating unit 3.

Therefore, as described above, the load heating heat exchanger 6 exchanges heat between refrigerant and antifreeze. The first snow-removing mode is assumed to be anti-icing processing for preventing a drain hole of the outdoor unit base 62, which will be described later, from being closed.

Next, a specific configuration of the indoor unit 9 will be described. The indoor unit 9 includes another part of the main refrigerant circuit 4. Specifically, the indoor unit 9 includes the indoor-unit-side heat exchanger 14 and the electronic expansion valve 15. Among the above components, the indoor-unit-side heat exchanger 14 functions as a use-side heat exchanger.

The indoor-unit-side heat exchanger 14 exchanges heat between refrigerant and air. Specifically, the indoor-unit-side heat exchanger 14 exchanges heat between the refrigerant flowing through the main refrigerant pipe 22 and indoor air sucked from the indoor unit 9 using a fan for the indoor unit 9, which is not illustrated in the figure. The indoor-unit-side heat exchanger 14 functions as a condenser; for example, during heating operation, and thus condenses and liquefies refrigerant. The indoor-unit-side heat exchanger 14 functions as an evaporator, for example, during cooling operation, and thus evaporates and gasifies refrigerant by causing the refrigerant to receive heat from the indoor air.

The electronic expansion valve 15 is formed of a valve whose opening degree may be adjusted. By controlling the opening degree of the valve, the electronic expansion valve 15 adjusts the pressure of refrigerant, the flow rate of refrigerant, and other related conditions in the indoor-unit-side heat exchanger 14. Therefore; the electronic expansion valve 15 forms a pressure-reducing unit for the main refrigerant circuit 4. That is, the electronic expansion valve 15 forms a pressure-adjusting unit for the main refrigerant circuit 4. Although it is assumed that one indoor unit 9 is provided in the above description, the present invention is not particularly limited to this example. For example, the air-conditioning apparatus 2 may include one outdoor unit 7 and a plurality of indoor units 9.

Next, a refrigeration cycle formed by the main refrigerant circuit 4 during heating operation of the air-conditioning apparatus 2 will be explained, with reference to the flow of refrigerant. Here, it is assumed that the controller 51 controls driving of each of the compressor 11, the four-way valve 12, the electronic expansion valve 15, the flow control device 17, the bypass circuit solenoid valve 32, the bypass circuit electronic expansion valve 34, and the pump 42. Furthermore, it is assumed that detection results of various sensors, which are not illustrated in the figure, as well as the bypass circuit temperature sensor 35, are transmitted to the controller 51. Furthermore, heating operation is assumed to be performed under an environment where the snow 55 does not reach the outdoor unit base 62, which will be described later.

In the outdoor unit 7, the compressor 11 compresses supplied refrigerant, and discharges the compressed refrigerant. The refrigerant that is discharged from the compressor 11 is high-temperature and high-pressure gas refrigerant. The high-temperature and high pressure gas refrigerant passes through the four-way valve 12 and the gas operation valve 13, flows out of the outdoor unit 7, and flows into the indoor unit 9. The refrigerant that has flowed into the indoor unit 9 passes through the indoor-unit-side heat exchanger 14 that functions as a condenser. At this time, at the indoor-unit-side heat exchanger 14, by being subjected to heat change with indoor air, the refrigerant condenses and liquefies, and heats air, for example, in the air-conditioned space. Therefore, the air-conditioning apparatus 2 is able to heat the air-conditioned space. Next, the refrigerant that has passed through the indoor-unit-side heat exchanger 14 is decompressed, turns into, for example, low-temperature and low-pressure, two-phase refrigerant, flows out of the indoor unit 9, and flows into the outdoor unit 7.

The low-temperature and low-pressure, two-phase refrigerant that has flowed into the outdoor unit 7 passes through the liquid operation valve 16, and flows into the outdoor-unit-side heat exchanger 19, which functions as an evaporator. The refrigerant that has passed through the outdoor-unit-side heat exchanger 19 is subjected to heat exchange with outdoor air to be evaporated and gasified, and sucked into the compressor 11 through the four-way valve 12 and the accumulator 20. The compressor 11 compresses the refrigerant again, and discharges the compressed refrigerant. As a result, the processing explained above is performed again, and the refrigerant circulates through the main refrigerant circuit 4.

In the basic heating operation described above, it is not necessary to supply refrigerant to the bypass pipe 31 to cause the refrigerant to flow through the bypass circuit 5. Therefore, the bypass circuit solenoid valve 32 is maintained to be closed.

In contrast, for example, heating operation is assumed to be performed under an environment where the amount of snow accumulation is large and the snow 55 reaches the outdoor unit base 62, which will be described later. In the assumed case, water generated during defrosting operation turns into ice at the outdoor unit base 62, and covers the drain hole of the outdoor unit base 62. Furthermore, under such a circumstance, the outdoor-unit-side heat exchanger 19 becomes frozen, and thus there is a possibility that the heating performance may degrade. Furthermore, the load heating unit 3 is assumed to be provided inside a snow-protection frame 81, which will be described later. Furthermore, to ensure the capacity of the load heating heat exchanger 6, the degree of subcooling is assumed to be obtained based on a detection result of the bypass circuit temperature sensor 35 and the opening degree of the bypass circuit electronic expansion valve 34 is assumed to be adjusted on the basis of the obtained degree of subcooling. At this time, to ensure a stable capacity of the load heating heat exchanger 6, for example, 10 (deg.) is assumed to be set as a target value of the degree of subcooling.

First, the air-conditioning apparatus 2 opens the bypass circuit solenoid valve 32, and supplies high-temperature and high-pressure refrigerant that has been discharged from the compressor 11 to the bypass circuit 5. Next, the air-conditioning apparatus 2 drives the pump 42 to cause antifreeze inside the load heating unit 3 to circulate. Then, the load heating heat exchanger 6 exchanges heat between the antifreeze that flows through the load heating unit 3 and the high-temperature and high-pressure refrigerant discharged from the compressor 11. Thus, the load heating unit 3 is heated. Therefore, since the load heating unit 3 melts snow below the outdoor unit base 62, the air-conditioning apparatus 2 is able to control freezing the drain hole.

The main refrigerant circuit 4 corresponds to a first refrigerant circuit according to the present invention. Furthermore, the bypass circuit 5 corresponds to a second refrigerant circuit according to the present invention. Furthermore, the main refrigerant pipe 22 corresponds to a refrigerant pipe according to the present invention. Furthermore, the bypass circuit solenoid valve 32 corresponds to a first solenoid valve according to the present invention. Furthermore, the electronic expansion valve 15 corresponds to an expansion device according to the present invention. Furthermore, the antifreeze that circulates in the load heating unit 3 corresponds to a heat medium according to the present invention.

The refrigerant that flows through the main refrigerant circuit 4 and the bypass circuit 5 is not particularly limited. For example, the refrigerant that flows through the main refrigerant circuit 4 and the bypass circuit 5 may be a single component refrigerant such as R22, a zeotropic refrigerant mixture such as R4070, a near-azeotropic refrigerant such as R410A, or a natural refrigerant such as CO₂. That is, as the refrigerant that flows through the main refrigerant circuit 4 and the bypass circuit 5, various refrigerants may be used.

Next, the arrangement configuration of the outdoor unit 7 and the load heating unit 3 will be explained with reference to FIG. 2. FIG. 2 is a diagram illustrating an example of an outer shape of the outdoor unit 7 according to Embodiment 1 of the present invention. As illustrated in FIG. 2, the outdoor unit 7 may include, as the outer shape, for example, a housing 61, the outdoor unit base 62, a snow-protection hood 63, a wind-bending plate 65, a wind-bending plate 67, and other components. The housing 61 accommodates, as described above, a part of the main refrigerant circuit 4. The outdoor unit base 62 is provided, for example, on the lower side of the housing 61, and supports the part of the main refrigerant circuit 4 accommodated in the housing 61. Specifically, the outdoor unit base 62 supports the compressor 11, the outdoor-unit-side heat exchanger 19, and other components. The outdoor unit base 62 has a drain hole, which is not illustrated in the figure.

The snow-protection hood 63 is, for example, provided above the housing 61, and accommodates a fan for the outdoor unit 7, which is not illustrated in the figure. The snow-protection hood 63 has an air outlet port 71. Air caused by the driving of the fan for the outdoor unit 7, which is not illustrated in the figure, is blown out through the air outlet port 71. The wind-bending plate 65 is provided at a position facing a part of the outdoor-unit-side heat exchanger 19 to form an air inlet port 73. The driving of the fan for the outdoor unit 7, which is not illustrated in the figure, causes outdoor air around the outdoor unit 7 to be sucked into the outdoor unit 7 through the air inlet port 73. The wind-bending plate 67 is provided at a position facing another part of the outdoor-unit-side heat exchanger 19 to form an air inlet port 75. The driving of the fan for the outdoor unit 7, which is not illustrated in the figure, causes outdoor air around the outdoor unit 7 to be sucked into the outdoor unit 7 through the air inlet port 75.

Below the outdoor unit 7, which has been described above, the snow-protection frame 81 is provided. Specifically, by providing the snow-protection frame 81 below the outdoor unit base 62, the snow-protection frame 81 supports the outdoor unit base 62, and the snow-protection frame 81 therefore supports the outdoor unit 7. Thus, the snow-protection frame 81 is able to support the outdoor unit 7 at a position away from a ground 85. The load heating unit 3 is provided inside the snow-protection frame 81. The load heating unit 3 may be placed at a position that is below the snow-protection frame 81 and that is not stepped on by the snow-protection frame 81.

The snow-protection frame 81 includes, for example, a base 82, legs 83, and diagonal braces 84. The base 82 faces the outdoor unit base 62, and serves as a base that supports the outdoor unit base 62. The legs 83 support, for example, the base 82 from the ground 8a Four legs 83 are provided for the base 82. The diagonal braces 84 reinforce the four legs 83.

The snowfall sensor 91 is provided at the snow-protection frame 81. For example, the snowfall sensor 91 is provided at the border between the base 82 of the snow-protection frame 81 and the outdoor unit base 62. The snowfall sensor 91 detects the snow 55 accumulated on the ground 85, and transmits a detection result to the controller 51, which has been described above with reference to FIG. 1. When the height of the snow-protection frame 81 from the ground 85 and the height of the mounted snowfall sensor 91 from the ground 85 are set in the controller 51, the snowfall sensor 91 may transmit only the information that the snow 55 is detected to the controller 51. However, the present invention is not particularly limited to this example. For example, when detecting the snow 55, the snowfall sensor 91 may calculate the height of the detected snow 55 from the ground 85 and transmit the calculation result to the controller 51.

The snowfall sensor 91 may be, for example, an infrared sensor that detects an obstacle using infrared rays. In this case, the snowfall sensor 91 with a low cost may be attained. Furthermore, the snowfall sensor 91 may include a plurality of infrared sensors and may be configured so that the plurality of infrared sensors are arranged with regular spaces therebetween vertically relative to the ground 85. In this case, the snowfall sensor 91 is able to detect the height of the detected snow 55 from the ground 85 in a stepwise manner. Furthermore, the snowfall sensor 91 may detect the snow 55 by detecting the outside air temperature and moisture. In this case, the snowfall sensor 91 detects the snow 55, based on a detection result of the outside air temperature and a determination as to whether or not moisture has been continuously detected for a preset time. Therefore, the snow 55 blown away from trees or another outdoor object by wind may be prevented from being falsely detected.

That is, the snowfall sensor 91 transmits information for adjusting the amount of snow accumulation below the snow-protection frame 81 to the controller 51. For example, in general, when the distance ΔL between the bottom of the outdoor unit base 62 and the snow 55 of the snow-protection frame 81 is 150 (μm), the drain hole, which is not illustrated in the figure, is not closed. As described above, the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81 only needs to be at least 150 (mm). Thus, for example, the position of the snowfall sensor 91 to be attached to the snow-protection frame 81 may be at the leg 83 of the snow-protection frame 81 that is approximately 150 (mm) away from the ground 85. Various configurations of the outdoor unit 7, the snow-protection frame 81, the snowfall sensor 91, and other components described above are merely examples, and the present invention is not particularly limited to these examples.

Next, the details of the controller 51, which has been schematically explained above, will be described with reference to FIG. 3. FIG. 3 is a diagram illustrating an example of a functional configuration of the controller 51 according to Embodiment 1 of the present invention. As illustrated in FIG. 3, the controller 51 includes, for example, a transmission/reception unit 101, an operation mode determination unit 103, a snow-removing mode start determination unit 105, a snow-removing mode ending determination unit 107, an operation stop determination unit 109, a snow-removing condition determination unit 111, an operation mode control unit 113, a snow-removing mode control unit 115, a main refrigerant circuit control unit 117, a bypass circuit control unit 121, a load heating unit control unit 123, and other units.

For example, the transmission/reception unit 101 receives a signal transmitted from the outside, and then converts the received signal into a signal to be processed in the controller 51. For example, the transmission/reception unit 101 converts the signal that has been processed in the controller 51 into a signal to be transmitted to the outside, and transmits the converted signal. The operation mode determination unit 103 determines the operation mode of the air-conditioning apparatus 2. The snow-removing mode start determination unit 105 determines whether or not to start the first snow-removing mode. The snow-removing mode ending determination unit 107 determines whether or not to end the first snow-removing mode. The operation stop determination unit 109 determines, based on the signal transmitted from the outside, whether or not to stop the operation.

The snow-removing condition determination unit 111 includes, for example, a snow accumulation amount determination unit 131 and a timer unit 133. The snow accumulation amount determination unit 131 determines the amount of snow accumulation, based on a detection result of the snowfall sensor 91. The snow accumulation amount determination unit 131 calculates the distance ΔL between the ground 85 and the surface of the snow 55, as an index corresponding to the amount of snow accumulation. For example, when the installation position of the snowfall sensor 91 is registered in advance and the registered position is assumed to be 150 (mm) from the ground 85, if the snowfall sensor 91 detects the snow 55, it may be determined that the distance ΔL between the ground 85 and the surface of the snow 55 has reached 150 (mm).

For example, the timer unit 133 counts the time during which the snowfall sensor 91 detects snow. For example, when the snowfall sensor 91 detects a value greater than 350 (mm) as the distance ΔL from the ground 85 to the snow 55, the timer unit 133 counts the time during which a value greater than 350 (mm) has been continuously detected. The determination of the amount of snow accumulation described above is merely an example, and the present invention is not particularly limited to this example.

The snow-removing condition determination unit 111 determines, based on a detection result of the snowfall sensor 91 and a preset start determination threshold, the start of the first snow-removing mode based on the amount of snow accumulation, and transmits the determination result to the snow-removing mode start determination unit 105. The snow-removing condition determination unit 111 determines, based on a detection result of the snowfall sensor 91 and a preset ending determination threshold, the ending of the first snow-removing mode based on the amount of snow accumulation and the elapsed time, and transmits the determination result to the snow-removing mode ending determination unit 107.

The operation mode control unit 113 transmits an instruction corresponding to the determined operation mode to the main refrigerant circuit control unit 117. When the start of the first snow-removing mode is determined, the snow-removing mode control unit 115 transmits an instruction corresponding to the start of the first snow-removing mode to each of the main refrigerant circuit control unit 117, the bypass circuit control unit 121, and the load heating unit control unit 123. When the ending of the first snow-removing mode is determined, the snow-removing mode control unit 115 transmits an instruction corresponding to the ending of the first snow-removing mode to each of the main refrigerant circuit control unit 117, the bypass circuit control unit 121, and the load heating unit control unit 123.

The main refrigerant circuit control unit 117 includes an electronic expansion valve control unit 141, a solenoid valve control unit 143, a compressor control unit 145, a fan control unit 147, and other components, and controls the flow rate, flowing direction, pressure, and other conditions of the refrigerant circulating in the main refrigerant circuit 4. The electronic expansion valve control unit 141 controls, for example, the opening degree of the electronic expansion valve 15 and the opening degree of the flow control device 17. The solenoid valve control unit 143 controls, for example, opening and closing of the gas operation valve 13 and opening and closing of the liquid operation valve 16. A four-way valve control unit 144 controls a switching operation of the four-way valve 12. The compressor control unit 145 controls driving of the compressor 11 depending on the operation frequency. The fan control unit 147 controls driving of a fan for the outdoor unit 7, which is not illustrated in the figure.

The bypass circuit control unit 121 includes a bypass circuit solenoid valve control unit 151, a bypass circuit electronic expansion valve control unit 153, and other components, and controls the flow rate, flowing direction, pressure, and other conditions of the refrigerant circulating in the bypass circuit 5. The bypass circuit solenoid valve control unit 151 controls opening and closing of the bypass circuit solenoid valve 32. The bypass circuit electronic expansion valve control unit 153 controls the opening degree of the bypass circuit electronic expansion valve 34. The load heating unit control unit 123 includes a pump control unit 155, and controls the flow rate, flowing direction, and other conditions of a heat medium circulating in the load heating unit 3, such as antifreeze.

The functional configuration explained above is merely an example, and the present invention is not particularly limited to this example. The configuration only needs to implement the functions described above. Next, an operation example of the controller 51 including the first snow-removing mode will be explained with reference to FIG. 4.

Operation of Embodiment 1

FIG. 4 is a flowchart for explaining a control example of the controller 51 according to Embodiment 1 of the present invention. In FIG. 4, as default setting, the case is assumed that the bypass circuit solenoid valve 32 is closed, a snow-protection flag is set to 0, a first distance threshold is set as a start determination threshold, a second distance threshold is set as an ending determination threshold, and a first time threshold is set as a determination of a detection continuous time. More specifically, the case is assumed that 250 (mm), for example, is set as the first distance threshold, 350 (mm), for example, is set as the second distance threshold, and 10 minutes is assumed to be set as the first time threshold.

The various setting examples explained above are merely examples, and the present invention is not particularly limited to the above examples. For example, the thresholds regarding the various distances and the threshold regarding the time are merely examples, and are changed depending on the environment under which the outdoor unit 7 is installed, that is, the amount of snow accumulation in the corresponding region.

For example, when the outdoor unit 7 is provided in a region with a greater amount of snow accumulation per unit time than the case assumed above, the snow 55 accumulates quickly. Therefore, the thresholds regarding the various distances may be set to be shorter than the values assumed above, and the threshold regarding the time may be set to be shorter than the value assumed above. Furthermore, for example, the snow-protection flag is merely used as an index indicating that a certain transition state continues to merely count the detection continuous time, and the present invention is not particularly limited to this example.

Furthermore, processing of steps S15 to S21 is assumed to be in the first snow-removing mode. That is, it is assumed that processing of steps S11 to S14 is first snow-removing-mode pre-process processing and processing of steps S22 to S24 is first snow-removing-mode post-process processing.

(First Snow-Removing-Mode Pre-Process Processing) (Step S11)

The controller 51 determines an operation mode.

(Step S12)

The controller 51 determines whether or not heating operation is being performed. When the heating operation is being performed, the controller 51 proceeds to step S13. In contrast, when the heating operation is not being performed, the controller 51 returns to step S11.

(Step S13)

The controller 51 obtains the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81.

(Step S14)

The controller 51 determines whether or not the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81 is shorter than the first distance threshold. When the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81 is shorter than the first distance threshold, the controller 51 proceeds to step S15. In contrast, when the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81 is not shorter than the first distance threshold, the controller 51 proceeds to step S11.

(First Snow-Removing-Mode Processing) (Step S15)

The controller 51 opens the bypass circuit solenoid valve 32.

(Step S16)

The controller 51 obtains the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81.

(Step S17)

The controller 51 determines whether or not the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81 is equal to or longer than the second distance threshold. When the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81 is equal to or longer than the second distance threshold, the controller 51 proceeds to step S18. In contrast, when the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81 is shorter than the second distance threshold, the controller 51 proceeds to step S24.

(Step S18)

The controller 51 sets the snow-protection flag to 1.

(Step 519)

The controller 51 counts the detection continuous time during which the snow-protection flag is continuously indicating 1,

(Step S20)

The controller 51 determines whether or not the detection continuous time during which the snow-protection flag is continuously indicating 1 exceeds the first time threshold. When the detection continuous time during which the snow-protection flag is continuously indicating 1 exceeds the first time threshold, the controller 51 proceeds to step S21. In contrast, when the detection continuous time during which the snow-protection flag is continuously indicating 1 does not exceed the first time threshold, the controller 51 returns to step S16.

(Step S21)

The controller 51 sets the snow-protection flag to 0, and proceeds to step S20.

(First Snow-Removing-Mode Post-Process Processing)

(Step S22)

The controller 51 closes the bypass circuit solenoid valve 32.

(Step S23)

The controller 51 determines whether or not an operation stop instruction arrives. When the operation stop instruction arrives, the controller 51 proceeds to step S23. In contrast, when the operation stop instruction does not arrive, the controller 51 returns to step S11.

(Step S24)

The controller 51 stops the operation, and ends the process.

(Effects of Embodiment 1

As a result, with the provision of the bypass circuit 5 in the outdoor unit 7, the load heating unit 3 that utilizes the refrigeration cycle heats a portion around the load heating unit 3. By providing the load heating unit 3 at the snow-protection frame 81, a portion around the snow-protection frame 81 is heated. Therefore, even if the snow 55 starts to accumulate on the snow-protection frame 81, by causing the load heating unit 3 to operate, the outdoor unit 7 is able to melt the snow 55 accumulated on the snow-protection frame 81.

Therefore, even if the outdoor unit 7 is installed under the environment with a low outside air temperature and a large amount of snow accumulation, water generated at the time of defrosting in heating operation does not turn into ice, and therefore the drain hole of the outdoor unit base 62 is not closed. Thus, the outdoor unit 7 is able to discharge water retaining in the outdoor unit base 62 to the outside. Therefore, the heat exchange efficiency of the outdoor-unit-side heat exchanger 19 is not reduced, and a degradation in the heating capacity may be controlled. Furthermore, with the circuit configuration in which refrigerant that has flowed out of the bypass pipe 31 flows into the accumulator 20, the compressor 11 does not suck liquid refrigerant. Consequently, the main refrigerant circuit 4 is able to increase the reliability of the outdoor unit 7.

Furthermore, since the snow-protection frame 81 does not need to be so high to exceed the maximum amount of snow accumulation that is assumed for a region where the outdoor unit 7 is provided, the height of the snow-protection frame 81 may be a height of design dimensions used for normal construction. Therefore, it is not necessary to ensure a sufficient height of the snow-protection frame 81, and the service performance of the outdoor unit 7 may thus be increased.

Furthermore, the load heating unit 3 may have a size so that the snow 55 accumulated around the snow-protection frame 81 can be melted. Thus, the load heating unit 3 is constructed with low cost. Furthermore, a heat-pump refrigeration cycle is used for a heat source that heats the load heating unit 3. Therefore, the load heating unit 3 that uses the heat-pump refrigeration cycle achieves a high safety in operation, and may be operated with a low-power consumption. Thus, the operational cost used for snow melting using the load heating unit 3 is low. Accordingly, the load heating unit 3 may be constructed at low cost, and the load heating unit 3 may be operated at low cost.

Therefore, the outdoor unit 7 may melt the snow 55 accumulated on the snow-protection frame 81 while the service performance is improved and a low cost is achieved. Therefore, the outdoor unit 7 is able to prevent water from turning into ice in the outdoor unit base 62 while the service performance is improved and a low cost is achieved. Consequently, the outdoor unit 7 is able to control ice formation and a deterioration in the air-conditioning capacity caused by water turning into ice in the outdoor unit base 62, while the service performance is improved and a low cost is achieved.

As described above, in Embodiment 1, the outdoor unit 7 includes a part of the main refrigerant circuit 4 formed by connecting the compressor 11, the indoor-unit-side heat exchanger 14, the electronic expansion valve 15, and the outdoor-unit-side heat exchanger 19 via the main refrigerant pipe 22, the bypass circuit 5 bypassing refrigerant discharged from the compressor 11 and flowing through the main refrigerant circuit 4, the controller 51 configured to control the flow rate of refrigerant flowing through the main refrigerant circuit 4 and the flow rate of refrigerant flowing through the bypass circuit 5, the outdoor unit base 62 supporting the compressor 11 and the outdoor-unit-side heat exchanger 19, the snow-protection frame 81 provided below the outdoor unit base 62, the snow-protection frame 81 supporting the outdoor unit base 62, and the load heating unit 3 provided to the snow-protection frame 81, the load heating unit 3 configured to heat a portion around the load heating unit 3 by exchanging heat between the heat medium flowing through the load heating unit 3 and the refrigerant flowing through the bypass circuit 5.

With the configuration described above, the outdoor unit 7 is able to prevent water from turning into ice in the outdoor unit base 62 while the service performance is improved and a low cost is achieved. Consequently, the outdoor unit 7 is able to control ice formation and a deterioration in the air-conditioning capacity caused by water turning into ice in the outdoor unit base 62, while the service performance is improved and a low cost is achieved.

Furthermore, in Embodiment 1, the bypass circuit 5 is connected to each of the pipe on the suction side of the compressor 11 and the pipe of the discharge side of the compressor 11, and includes the bypass pipe 31 that bypasses refrigerant and the bypass circuit solenoid valve 32 that adjusts the flow rate of the refrigerant flowing in the bypass pipe 31.

Furthermore, in Embodiment 1, the snow-protection frame 81 includes the snowfall sensor 91 that detects the snow 55 accumulated around the snow-protection frame 81, and the controller 51 causes the load heating unit 3 to operate by controlling the bypass circuit solenoid valve 32 depending on the distance ΔL between the outdoor unit base 62 and the snow 55 detected by the snowfall sensor 91.

Furthermore, in Embodiment 1, the load heating unit 3 is provided inside or below the snow-protection frame 81.

Furthermore, in Embodiment 1, the heat medium is antifreeze.

With the configuration described above, the outdoor unit 7 is able to prevent water from turning into ice in the outdoor unit base 62 while, particularly remarkably, the service performance is improved and a low cost is achieved.

Embodiment 2

A difference from Embodiment 1 is that snow may be removed even during a heating stop period, by providing a gas refrigerant solenoid valve 36 between the discharge side of the compressor 11 and the gas operation valve 13 so that refrigerant is not supplied to the indoor-unit-side heat exchanger 14.

Configuration of Embodiment 2

FIG. 5 is a diagram illustrating an example of the schematic configuration of the air-conditioning system 1 according to Embodiment 2 of the present invention. As illustrated in FIG. 5, the gas refrigerant solenoid valve 36 is provided between the four-way valve 12 and the gas operation valve 13. That is, during heating operation, when the four-way valve 12 is switched so that the discharge side of the compressor 11 is connected to the indoor-unit-side heat exchanger 14, the gas refrigerant solenoid valve 36 can be provided between the discharge side of the compressor 11 and the gas operation valve 13, as described above.

The gas refrigerant solenoid valve 36 corresponds to a second solenoid valve according to the present invention.

Providing the gas refrigerant solenoid valve 36 enables control as to whether or not to cause gas refrigerant to flow into the indoor-unit-side heat exchanger 14. That is, the gas refrigerant solenoid valve 36 is able to control inflow of gas refrigerant into the indoor unit 9.

For example, the heating stop time is assumed to increase. In this case, during the heating operation stop period, the load heating unit 3 does not operate. Therefore, there is a possibility that the snow 55 may reach the bottom of the outdoor unit base 62. Furthermore, if the snow 55 continues to be at the bottom of the outdoor unit base 62 for a long time, the drain hole arranged at the outdoor unit base 62 may be closed. For example, when a scheduled operation is performed so that heating operation is stopped at 21 o'clock and resumes at 7 o'clock the next day, the heating operation stop period continues from 21 o'clock to 7 o'clock the next day. Therefore, the load heating unit 3 does not operate for ten hours. Under such circumstances, it is assumed that, in a region with a large amount of snow accumulation, the snow 55 accumulated on the ground 85 may reach the bottom of the outdoor unit base 62.

Thus, when certain conditions are satisfied after the heating operation is stopped, the controller 51 causes the gas refrigerant solenoid valve 36 to operate and controls so that no refrigerant is supplied to the indoor-unit-side heat exchanger 14. Next, an example of the functional configuration of the operation explained above will be described with reference to FIG. 6.

FIG. 6 is a diagram illustrating an example of a functional configuration of the controller 51 according to Embodiment 2 of the present invention. As illustrated in FIG. 6, the transmission/reception unit 101, the snow-removing mode start determination unit 105, the snow-removing mode ending determination unit 107, the snow-removing condition determination unit 111, the operation mode control unit 113, the snow-removing mode control unit 115, the main refrigerant circuit control unit 117, the bypass circuit control unit 121, and the load heating unit control unit 123 are provided. That is, in FIG. 6 for explaining Embodiment 2, compared to the case of Embodiment 1 described above with reference to FIG. 3, a functional configuration without the operation mode determination unit 103 and the operation stop determination unit 109 is provided.

Furthermore, in the functional configuration illustrated in FIG. 6 for explaining Embodiment 2, the transmission/reception unit 101, the snow-removing mode start determination unit 105, the snow-removing mode ending determination unit 107, the operation mode control unit 113, the snow-removing mode control unit 115, the bypass circuit control unit 121, and the load heating unit control unit 123 are similar to those in FIG. 3 explained in Embodiment 1. Therefore, explanation for those similar components will be omitted.

In the configuration of the snow-removing condition determination unit 111, the snow accumulation amount determination unit 131 is similar to the functional configuration illustrated in FIG. 3. Therefore, explanation for the snow accumulation amount determination unit 131 will be omitted. In the configuration of the snow-removing condition determination unit 111, the timer unit 113 uses the stop time, the elapsed time, the detection continuous time, and various thresholds for counting. A setting determination unit 135 determines whether or not the second snow-removing mode is set. The second snow-removing mode is, for example, set by a dip switch, a rotary switch, or other switches provided at the outdoor unit 7. In the configuration of the main refrigerant circuit control unit 117, a gas refrigerant solenoid valve control unit 149 is a newly-added functional configuration. The gas refrigerant solenoid valve control unit 149 controls opening and closing of the gas refrigerant solenoid valve 36.

Next, an operation in the second snow-removing mode will be explained with reference to FIG. 7. As assumed settings, in the second snow-removing-mode pre-process processing, the operation stop state is set as a stop flag, a threshold for the time during which the operation stop state continues is set as a second time threshold, the information that the operation stop state has continued for a predetermined time is set as a first start threshold, the first distance threshold is set as described above, the case where the distance ΔL satisfies a condition of being shorter than the first distance threshold is set as a second start threshold, and the state in which the second snow-removing mode is set is set as a third start threshold. Furthermore, as the second time threshold is, for example, a continuous time T1 is set. Furthermore, as the third time threshold is, for example, a continuous time T2 is set.

Furthermore, as assumed settings, in second snow-removing-mode processing, the second distance threshold and the detection continuous time are set as described above, the case where the detection continuous time exceeds the first time threshold is set as a first ending threshold, and the case where the elapsed time is equal to or longer than the third time threshold is set as a second ending threshold.

Furthermore, for example, the elapsed time mentioned here represents the elapsed time from the start of control by the controller 51 to the current time, and the third time threshold is set to, for example, the continuous time T2, as a threshold for the determination of the elapsed time.

As a default value, 0 is set for each of the first start threshold, the second start threshold, and the third start threshold. Furthermore, as a default value, 0 is set for each of the first ending threshold and the second ending threshold. Furthermore, a value corresponding to the surrounding environment under which the outdoor unit 7 is provided is set for each of the continuous time T1 and the continuous time T2.

A heating prohibition flag that is set in the second snow-removing-mode processing and reset in the second snow-removing-mode post-process processing indicates that the heating operation is prohibited during the second snow-removing mode, and the heating prohibition flag is not particularly limited to this example. In short, the second snow-removing mode and the heating operation only need to be operations to be exclusively controlled. Furthermore, for example, the snow-protection flag is merely used as an index indicating that a certain transition state continues to merely count the detection continuous time, and the present invention is not particularly limited to this example.

The various setting examples described above are merely examples, and the present invention is not particularly limited to the above examples. For example, the thresholds regarding the various distances and the thresholds regarding the time are merely examples, and are changed depending on the environment under which the outdoor unit 7 is installed, that is, the amount of snow accumulation in the corresponding region,

Furthermore, processing of steps S44 to S58 is assumed to be the second snow-removing-mode processing. Furthermore, processing of steps S31 to S43 is assumed to be second snow-removing-mode pre-process processing. Furthermore, processing of steps S59 to S61 is assumed to be second snow-removing-mode post-process processing.

Operation of Embodiment 2

FIG. 7 is a flowchart for explaining a control example of the controller 51 according to Embodiment 2 of the present invention. It is assumed that, while the heating prohibition flag is set to 1, the heating operation is prohibited.

(Second Snow-Removing-Mode Pre-Process Processing) (Step S31)

The controller 51 initializes various flags.

(Step S32)

The controller 51 determines whether or not an operation is stopped. When the operation is stopped, the controller 51 proceeds to step S33. In contrast, when the operation is not stopped, the controller 51 returns to step S32.

(Step S33)

The controller 51 sets a stop flag to 1.

(Step S34)

The controller 51 counts a stop time during which the stop flag is continuously indicating 1,

(Step S35)

The controller 51 determines whether or not the stop time exceeds the second time threshold. When the stop time exceeds the second time threshold, the controller 51 proceeds to step S36. In contrast, when the stop time does not exceed the second time threshold, the controller 51 returns to step S34.

(Step S36)

The controller 51 sets the first start threshold to 1.

(Step S37)

The controller 51 obtains the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81.

(Step S38)

The controller 51 determines whether or not the distance ΔL is shorter than the first distance threshold. When the distance ΔL is shorter than the first distance threshold, the controller 51 proceeds to step S39. In contrast, when the distance ΔL is not shorter than the first distance threshold, the controller 51 proceeds to step S32.

(Step S39)

The controller 51 sets the second start threshold to

(Step S40)

The controller 51 determines whether or not the second snow-removing mode is set. When the second snow-removing mode is set, the controller 51 proceeds to step S41. In contrast, when the second snow-removing mode is not set, the controller 51 returns to step S32.

(Step S41)

The controller 51 sets the third start threshold to 1.

(Step S42)

The controller 51 executes AND operation of the first start threshold, the second start threshold, and the third start threshold.

(Step S43)

The controller 51 determines whether or not an execution result of the AND operation is 1. When the execution result of the AND operation is 1, the controller 51 proceeds to step S44. In contrast, when the execution result of the AND operation is not 1, the controller 51 returns to step S32.

(Second Snow-Removing-Mode Processing) (Step S44)

The controller 51 closes the gas refrigerant solenoid valve 36.

(Step S45)

The controller 51 opens the bypass circuit solenoid valve 32.

(Step S46)

The controller 51 sets the heating prohibition flag for the indoor-unit-side heat exchanger 14 to 1. That is, the controller 51 sets the heating prohibition state for the indoor-unit-side heat exchanger 14.

(Step S47)

The controller 51 counts the elapsed time after the start of control.

(Step S48)

The controller 51 obtains the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81.

(Step S49)

The controller 51 determines whether or not the distance ΔL is equal to or longer than the second distance threshold. When the distance ΔL is equal to or longer than the second distance threshold, the controller 51 proceeds to step S50. In contrast, when the distance ΔL is shorter than the second distance threshold, the controller 51 proceeds to step S58.

(Step S50)

The controller 51 sets the snow-protection flag to 1.

(Step S51)

The controller 51 counts the detection continuous time during which the snow-protection flag is continuously indicating 1.

(Step S52)

The controller 51 determines whether or not the detection continuous time exceeds the first time threshold. When the detection continuous time exceeds the first time threshold, the controller 51 proceeds to step S53. In contrast, when the detection continuous time does not exceed the first time threshold, the controller 51 returns to step S51.

(Step S53)

The controller 51 sets the first ending threshold to 1.

(Step S54)

The controller 51 determines whether or not the elapsed time is equal to or longer than the third time threshold. When the elapsed time is equal to or longer than the third time threshold, the controller 51 proceeds to step S55. In contrast, when the elapsed time is shorter than the third time threshold, the controller 51 proceeds to step S56.

(Step S55)

The controller 51 sets the second ending threshold to 1.

(Step S56)

The controller 51 executes OR operation of the first ending threshold and the second ending threshold.

(Step S57)

The controller 51 determines whether or not an execution result of the OR operation is 1. When the execution result of the OR operation is 1, the controller 51 proceeds to step S59. In contrast, when the execution result of the OR operation is not 1, the controller 51 returns to step S48,

(Step S58)

The controller 51 sets the snow-protection flag to 0, and returns to step S48. (Second Snow-removing-mode Post-process Processing)

(Step S59)

The controller 51 opens the gas refrigerant solenoid valve 36.

(Step S60)

The controller 51 closes the bypass circuit solenoid valve 32,

(Step S61)

The controller 51 sets the heating prohibition flag for the indoor-unit-side heat exchanger 14 to 0, and ends the process. That is, the controller 51 releases the heating prohibition state for the indoor-unit-side heat exchanger 14.

Effects of Embodiment 2

As a result, the outdoor unit 7 does not enter heating operation when the second snow-removing mode is entered. Therefore, high-temperature and high-pressure gas refrigerant is not supplied to the indoor-unit-side heat exchanger 14, and the high-temperature and high-pressure gas refrigerant discharged from the compressor 11 may be supplied to the bypass circuit 5. Therefore, even when the heating operation is stopped, the outdoor unit 7 may cause the load heating heat exchanger 6 to exchange heat between refrigerant and a heat medium. Therefore, the load heating unit 3 may be heated.

Consequently, the outdoor unit 7 is able to melt the snow 55 accumulated below the outdoor unit base 62. As a result, snow may be removed. Thus, even if the heating operation is stopped, the outdoor unit 7 is able to remove the snow 55 accumulated below the snow-protection frame 81.

As described above, in Embodiment 2, the gas refrigerant solenoid valve 36 that is provided between the indoor-unit-side heat exchanger 14 and the discharge side of the compressor 11 and adjusts the flow rate of the refrigerant to be supplied to the indoor-unit-side heat exchanger 14, is further provided, and the controller 51 closes the gas refrigerant solenoid valve 36 and opens the bypass circuit solenoid valve 32 when heating operation is stopped.

With the above configuration, the outdoor unit 7 is able to remove snow even during the heating stop period.

Embodiment 3

A difference from Embodiment 1 and Embodiment 2 is that, during snow removal, the operation frequency of the compressor 11 is set to be higher than normal.

Configuration of Embodiment 3

FIG. 8 is a diagram illustrating an example of a functional configuration of the controller 51 according to Embodiment 3 of the present invention, Differences from Embodiment 1 and Embodiment 2 is that a set value of rapid snow-removing operation frequency is transmitted to the compressor control unit 145. The rapid snow-removing operation frequency may be set by a dip switch or another device provided in an electric component box of the outdoor unit 7, which is not illustrated in the figure. The rapid snow-removing operation frequency is, for example, set to be higher than the operation frequency for a normal operation. The rapid snow-removing operation frequency may be configured to be set when the second snow-removing mode is set.

Operation of Embodiment 3

FIG. 9 is a flowchart for explaining a control example of the controller 51 according to Embodiment 3 of the present invention. A difference from Embodiment 2 is that processing not included in the second snow-removing mode is added. The added processing is a technique for controlling the compressor 11 using the rapid snow-removing operation frequency. It is assumed that, while the heating prohibition flag is set to 1, the heating operation is prohibited.

Furthermore, processing of steps S84 to S99 is assumed to be third snow-removing-mode processing. Furthermore, processing of steps S71 to S83 is assumed to be second snow-removing-mode pre-process processing. Furthermore, processing of steps S100 to S103 is assumed to be second snow-removing-mode post-process processing.

(Third Snow-Removing-Mode Pre-Process Processing) (Step S71)

The controller 51 initializes various flags.

(Step S72)

The controller 51 determines whether or not an operation is stopped. When the operation is stopped, the controller 51 proceeds to step S73. In contrast, when the operation is not stopped, the controller 51 returns to step S72.

(Step S73)

The controller 51 sets a stop flag to 1.

(Step S74)

The controller 51 counts a stop time during which the stop flag is continuously indicating 1.

(Step S75)

The controller 51 determines whether or not the stop time exceeds the second time threshold. When the stop time exceeds the second time threshold, the controller 51 proceeds to step S76. In contrast, when the stop time does not exceed the second time threshold, the controller 51 returns to step S74.

(Step S76)

The controller 51 sets the first start threshold to

(Step S77)

The controller 51 obtains the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81.

(Step S78)

The controller 51 determines whether or not the distance ΔL is shorter than the first distance threshold. When the distance ΔL is shorter than the first distance threshold, the controller 51 proceeds to step S79. In contrast, when the distance ΔL is not shorter than the first distance threshold, the controller 51 proceeds to step S72.

(Step S79)

The controller 51 sets the second start threshold to 1.

(Step S80)

The controller 51 determines whether or not the second snow-removing mode is set. When the second snow-removing mode is set, the controller 51 proceeds to step S81. In contrast, when the second snow-removing mode is not set, the controller 51 returns to step S72,

(Step S81)

The controller 51 sets the third start threshold to 1.

(Step S82)

The controller 51 executes AND operation of the first start threshold, the second start threshold, and the third start threshold.

(Step S83)

The controller 51 determines whether or not an execution result of the AND operation is 1. When the execution result of the AND operation is 1, the controller 51 proceeds to step S84. In contrast, when the execution result of the AND operation is not 1, the controller 51 returns to step S72.

(Third Snow-Removing-Mode Processing) (Step S84)

The controller 51 closes the gas refrigerant solenoid valve 36.

(Step S85)

The controller 51 opens the bypass circuit solenoid valve 32.

(Step S86)

The controller 51 controls the compressor 11 using the rapid snow-removing operation frequency.

(Step S87)

The controller 51 sets a heating prohibition flag for the indoor-unit-side heat exchanger 14 to 1. That is, the controller 51 sets the heating prohibition state for the indoor-unit-side heat exchanger 14.

(Step S88)

The controller 51 counts the elapsed time after the start of control.

(Step S89)

The controller 51 obtains the distance ΔL between the outdoor unit base 62 and the snow 55 at the snow-protection frame 81.

(Step S90)

The controller 51 determines whether or not the distance ΔL is equal to or longer than the second distance threshold. When the distance ΔL is equal to or longer than the second distance threshold, the controller 51 proceeds to step S91. In contrast, when the distance ΔL is shorter than the second distance threshold, the controller 51 proceeds to step S99.

(Step S91)

The controller 51 sets the snow-protection flag to 1.

(Step S92)

The controller 51 counts the detection continuous time during which the snow-protection flag is continuously indicating 1.

(Step S93)

The controller 51 determines whether or not the detection continuous time exceeds the first time threshold. When the detection continuous time exceeds the first time threshold, the controller 51 proceeds to step S94. In contrast, when the detection continuous time does not exceed the first time threshold, the controller 51 returns to step S92.

(Step S94)

The controller 51 sets the first ending threshold to 1.

(Step S95)

The controller 51 determines whether or not the elapsed time is equal to or longer than the third time threshold. When the elapsed time is equal to or longer than the third time threshold, the controller 51 proceeds to step S96. In contrast, when the elapsed time is shorter than the third time threshold, the controller 51 proceeds to step S97.

(Step S96)

The controller 51 sets the second ending threshold to 1.

(Step S97)

The controller 51 executes OR operation of the first ending threshold and the second ending threshold.

(Step S98)

The controller 51 determines whether or not an execution result of the OR operation is 1. When the execution result of the OR operation is 1, the controller 51 proceeds to step S100. In contrast, when the execution result of the OR operation is not 1, the controller 51 returns to step S89.

(Step S99)

The controller 51 sets the snow-protection flag to 0, and returns to step S89.

(Third Snow-Removing-Mode Post-Process Processing) (Step S100)

The controller 51 opens the gas refrigerant solenoid valve 36.

(Step S101)

The controller 51 closes the bypass circuit solenoid valve 32.

(Step S102)

The controller 51 returns the operation frequency of the compressor 11 to the normal operation frequency.

(Step S103)

The controller 51 sets the heating prohibition flag for the indoor-unit-side heat exchanger 14 to 0, and ends the process. That is, the controller 51 releases the heating prohibition state for the indoor-unit-side heat exchanger 14.

Effects of Embodiment 3

As a result, since the operation frequency of the compressor 11 is changed depending on the installation environment, during snow removal, the outdoor unit 7 can drive the compressor 11 at a rapid snow-removing operation frequency, which is higher than the normal operation frequency of the compressor 11. Therefore, since the outdoor unit 7 drives the compressor 11 at an operation frequency corresponding to the installation environment, the amount of heat exchange at the load heating heat exchanger 6 may be increased depending on the amount of snow accumulation. Consequently, the outdoor unit 7 can increase the amount of heating per unit time of the load heating unit 3. Thus, by changing settings depending on the amount of snow accumulation, the outdoor unit 7 may reduce the snow removal time and increase the amount of snow removal per unit time.

As described above, in Embodiment 3, the switching unit 52 is further provided, and the controller 51 increases the operation frequency of the compressor 11 depending on the setting contents of the switching unit 52 when the heating operation is stopped.

With this configuration, the outdoor unit 7 may reduce the snow removal time and increase the amount of snow removal per unit time.

In Embodiments 1 to 3, the outdoor unit 7 of the air-conditioning apparatus 2 has been described. However, for example, as a system in which the outdoor-unit-side heat exchanger 19 functions as an evaporator, even a refrigeration system of another type that is driven in a heat-pump method, such as a hot water system, may use the techniques described in Embodiments 1 to 3.

REFERENCE SIGNS LIST

1: air-conditioning system, 2: air-conditioning apparatus, 3: load heating unit, 4: main refrigerant circuit, 5: bypass circuit, 6: load heating heat exchanger, 7: outdoor unit, 9: indoor unit, 11: compressor, 12: four-way valve, 13: gas operation valve, 14: indoor-unit-side heat exchanger, 15: electronic expansion valve, 16: liquid operation valve, 17: flow control device, 18: heat exchanger, 19: outdoor-unit-side heat exchanger, 20: accumulator, 22: main refrigerant pipe, 23: sub-refrigerant pipe, 31: bypass pipe, 32: bypass circuit solenoid valve, 34: bypass circuit electronic expansion valve, 35: bypass circuit temperature sensor, 36: gas refrigerant solenoid valve, 41: heating member, 42: pump, 43: heating pipe, 44: load heating refrigerant pipe, 51:

controller, 52: switching unit, 55: snow, 61: housing, 62: outdoor unit base, 63: snow-protection hood, 65, 67: wind-bending plate, 71: outlet port, 73, 75: inlet port, 81: snow-protection frame, 82: base, 83: leg, 84: diagonal brace, 85: ground, 91: snowfall sensor, 101: transmission/reception unit, 103: operation mode determination unit, 105: snow-removing mode start determination unit, 107: snow-removing mode ending determination unit, 109: operation stop determination unit, 111: snow-removing condition determination unit, 113: operation mode control unit, 115: snow-removing mode control unit, 117: refrigerant circuit control unit, 121: bypass circuit control unit, 123: load heating unit control unit, 131: snow accumulation amount determination unit, 133: timer unit, 135: setting determination unit, 141: electronic expansion valve control unit, 143: solenoid valve control unit, 144: four-way valve control unit, 145: compressor control unit, 147: fan control unit, 149: gas refrigerant solenoid valve control unit, 151: bypass circuit solenoid valve control unit, 153: bypass circuit electronic expansion valve, 155: pump control unit 

1. An outdoor unit comprising: a part of a first refrigerant circuit formed by connecting a compressor, an indoor-unit-side heat exchanger, an expansion device, and an outdoor-unit-side heat exchanger via a refrigerant pipe; a second refrigerant circuit bypassing refrigerant discharged from the compressor and flowing through the first refrigerant circuit; an outdoor unit base supporting the compressor and the outdoor-unit-side heat exchanger; a snow-protection frame provided below the outdoor unit base, the snow-protection frame supporting the outdoor unit base; and a load heating unit provided to the snow-protection frame, the load heating unit configured to heat a portion around the load heating unit by exchanging heat between a heat medium flowing through the load heating unit and refrigerant flowing through the second refrigerant circuit.
 2. The outdoor unit of claim 1, wherein the second refrigerant circuit includes a bypass pipe connected to each of a pipe on a suction side of the compressor and a pipe on a discharge side of the compressor to bypass the refrigerant, and a first solenoid valve adjusting a flow rate of the refrigerant flowing in the bypass pipe.
 3. The outdoor unit of claim 2, further comprising a controller configured to control a flow rate of refrigerant flowing through the first refrigerant circuit and a flow rate of the refrigerant flowing through the second refrigerant circuit, wherein the snow-protection frame includes a snowfall sensor detecting snow accumulated around the snow-protection frame, and wherein the controller causes the load heating unit to operate by controlling the first solenoid valve depending on a distance between the outdoor unit base and the snow detected by the snowfall sensor.
 4. The outdoor unit of claim 3, further comprising a second solenoid valve provided between the indoor-unit-side heat exchanger and the discharge side of the compressor, the second solenoid valve adjusting a flow rate of the refrigerant to be supplied to the indoor-unit-side heat exchanger, wherein the controller closes the second solenoid valve and opens the first solenoid valve when heating operation is stopped.
 5. The outdoor unit of claim 4, further comprising a switching unit, wherein the controller increases an operation frequency of the compressor depending on setting contents of the switching unit when the heating operation is stopped.
 6. The outdoor unit of claim 1, wherein the load heating unit is provided inside or below the snow-protection frame.
 7. The outdoor unit of claim 1, wherein the heat medium is antifreeze. 